Expand all GenAI modules to deep-dive depth: RAG, VectorDB, Agents, MultiAgent, Function Calling, Evaluation, Guardrails, Deployment, Production Patterns - comprehensive concepts, code examples, and interview questions

feat: Deep-dive expansion of LLM Fundamentals, Transformers, and Fine-Tuning modules

feat: Expand Hugging Face module to comprehensive deep-dive

feat: Add GenAI & Agentic AI module (13 topics)